The invention relates to a device for connecting structural components, comprising a base part attached to one of said components, a spacer which is in-threaded engagement with the base part and has an end supported at the other structural component, and a connecting screw which is inserted frictionally engaged through the spacer.
A known device of this type is described in U.S. Pat. No. 4,682,906 and is used to connect two structural components, which are disposed at a particular distance from one another, with the help of the connecting screw, without distorting the structural components as the connecting screw is tightened. The connecting screw is inserted, for example, through the structural component, which is to be supported at the spacer, and is then screwed into an internal thread of the other structural component which is connected with the base part. During this screwing-in motion, the spacer is taken along by friction. The thread between the spacer and the base part is a left-handed thread, so that the spacer is screwed further out of the base part and approaches the structural component, which is held by the head of the connecting screw, until this component finally lies in contact with the front surface of the spacer.
However, if the distance between the structural components which are to be connected is greater than the maximum adjusting path of the spacer, it may happen that, as the connecting screw is screwed in, the spacer is screwed completely out of the base part. Since the spacer in this case is accessible only with difficulty, if at all, it is difficult to restore the threaded engagement between the spacer and the base part.
In the state of the connecting device as delivered, the spacer normally is screwed completely into the base part. From practice, a connecting device is known, in which the spacer in this position is in contact with a stop and, in addition is held in position by a resilient tab. It must however be possible to overcome the resistance of this tab when the connecting screw is screwed in. Accordingly, it cannot be excluded that, because of improper handling or jarring, the spacer, before use of the connecting device, becomes detached completely from the base part, so that the parts of the connecting device fall apart and are lost. Another embodiment of a connecting device of this type is disclosed in applicant""s co-pending U.S. patent application Ser. No. 09/920,201.
It is an object of the invention to provide a device of the type indicated above, in which the spacer and the base part are held together so as to be prevented from getting lost.
According to the invention, this object is achieved by the fact that the movement of the spacer relative to the base part in one direction is limited by a shoulder that is formed at an end of the threaded portion of the spacer and engages an abutment at the base part, which abutment becomes effective only after the spacer and the base part have been assembled.
Thus, in the device according to the invention, it is possible that the spacer is initially screwed into the base part and then the abutment is made effective, so that the spacer can no longer be screwed out of the base part completely. If necessary, the movement of the spacer relative to the base part in the other direction may be limited by normal stops, so that it is possible, neither, to screw the spacer completely through the base part. In this way, the spacer and the base part, once assembled, are held together so that they may not get lost.
In one embodiment, the abutment, which becomes effective only after assembly, is formed by a spring member which projects radially inward from the base part, for example a spring member in the form of a resilient tab which retreats, when the spacer is screwed in, and which then locks behind the shoulder of the spacer.
In another embodiment, the abutment is rigidly provided on a jacket into which a threaded sleeve is press-fitted. In this embodiment, the spacer is at first screwed into the threaded sleeve, and only then is the threaded sleeve pressed into the jacket of the base part, so that the abutment is made effective.